Electric furnace.



No. 658,3I5.

A. H. COWLES.

ELECTRIC FURNACE.

Patented Sept. I8. I900.

(Application filed Oct. 22, 1895.)

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.YHE uonms PETERS co wow-um ASNVNKYDN c INVENTDFI.

ATTUFINEY.

No. 658,3l5.

Patented Sept. l8, I900. A. H. CUWLES.

ELECTRIC FURNACE.

(Application filed Oct. 22, 1895.)

3 Shets-Sheat 2.

(No Model.)

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' Patented Sept. l8, I900. A. H. COWLES.

ELECTRIC FURNACE.

(Application filed Oct. 22, 1895.)

(No Model.)

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WAQWM UNITED STATES ALFRED H. COWLES, OF CLEVELAND, OHIO, ASSIGNOR TOTHE ELECTRIC SMELTING AND ALUMINUM COMPANY, OF ILLINOIS.

ELECTRIC FU RNACE.

SPECIFICATION forming part of Letters Patent No. 658,315, datedSeptember 18, 1900.

Application filed October 22, 1895. serial No. 566,567. \No model.)

To all whom, it may concern.-

Be it known that I, ALFRED I'I. COWLEs, a citizen of the United States,residing at Cleveland, in the county of Cuyahoga and State of Ohio, haveinvented certain new and useful Improvements in Electric Furnaces; and Ido hereby declare the following to be a full,clear, and exactdescription of the invention, such as will enable others skilled in theart to which it appertains to make and use the same, reference being hadto the accompanying drawings, and to letters of reference markedthercon,which form a part of this specification.

In certain companion applications heretofore made I have shown anddescribed certain improvements in electric smelting processes andfurnaces whereby a control can be secured of the field of heat in anelectric furnace by means of an alternating flow of gas therethrough.This is specially set forth in an application filed by me July 6, 1895,Serial No. 555,116, and I have also described an improvement embodying acombination of a regenerative furnace with an electric furnace wherebythe heat of combustion can be em ployed up to the highest temperaturethat the coinbustion-furnace is capable of producing, and then thefinish can be given with electric heat, this latter improvement beingset out in an application filed by me August 1%), 1895, Serial No.559,728.

A further improvement in the art of electric smelting and in furnacestherefor involves a combination of the regenerative principal with anelectric furnace and the coincidentapplication of the heat of hot gaseswith the heating, electrolytic, and reducing efiects of an electricfurnace or the successive application of the heat of combustion andelectric heat to the material under treatment in place, and thisimprovement constitutes the subject-matter of the present invention.

The object in view is to provide asmelting apparatus which shall admitof the smelting or reduction of the refractory ores or compounds beingcarried on very much more economically than ever before and on a largerscale and to this end shall economize the heat and employ the heat ofcombustion, supplemented by electrical heat and energy, to

PATENT Cri ics,

render the final reduction possible with a small consumption ofelectrical energy. The practical construction of such a furnace requiresthe application of the water-jacketing principle, which is also setforth in a prior application, Serial No. 301,377, of July 27, 1889, forit becomes desirable in the opera tion of a furnace with such high heatsto confine the spread of high temperature within definite bounds inorder that they may be run continuously. This result I secure by thecombinat,-ion,witl1an electric fu rnace,whether of the incandescent orare type, of a regenerative flow of gases therethrough and theutilization of the heat of the escaping gases for the purpose of heatregeneration. For example, I locate the electric furnace between twobodies of carbon, coke, or fuel and pass through the electric furnaceand the juxtaposed masses of carbon a current of air or a current ofmixed air and gas or of gases may be preheated in heating-stoves or byre generative checkwork, or the preheating feature may be omitted. Ineither case the bodies of carbon act as regenerative masses and witheach reversal of the flow of gas therethrough increase the temperature.Thus in an apparatus having masses of incandescent fuel in conjunctionwith an electric smelting-chamher charged with ore to be reduced or withmaterial for metallurgical treatment, all of the chambers being closedin and so connected that a current of airor gases can pass successivelythrough them, the effect is that the inflowing current of gas or airburns in the first coinbustion-chamber or fuel-body, and

the heat from the hot gases passing therefrom through the electricfurnace-chaml'ier is supplemented by the electric heat and gives thereina temperature which is higher than is possible by combustion, and thistemperature, together with possible electrolytic and reducing effects ofthe current, effects reduction of the most refractorycompounds, 5 suchas lime, clay, sand, aluminium, &c. It will be understood that thetemperature obtainable under these conditions where there is a movementof gases through a field of electric heat has limitations due to thetem- IOO perature of dissociation of carbonic oxid. This limitation doesnot extend to the arc itthis combustion chamber.

self, but to the temperature of the chamber outside of the are, whichwill be held down to that of the dissociation of carbonic oxid, andhence 1 preferably so arrange the furnace that the flow of hotgasthrough the electric furnace-chamber will be removed from the immediatecenter of electric heat. and will be through the material approachingthe electric-heat center, so that the ore will receive the heatingbenefit of the hot gases within the electric furnace-chainber prior tothe finishing electric heat; but at the same time the high temperatureof the electrically-heatet'l zone immediately around the arc center willnot be reduced by the gas-flow. The hot gases issuing from the electricchamber pass through another combustion chamber or body of fuel and addheat thereto by reason of the hot gases being hotter than theincandescent fuel,and the gases after passing therethrough go preferablyto heating-stoves to effect further economies in the process. After theapparatus has been thus running for a proper interval of time the flowis reversed and what may be called the second combustion-chamber, withits superheated mass of incandescent fuel, becomes the activecombustion-chamber of the series. The infiowing air or gas or mixed airand gas now flows through the interstices of the mass of superheatedmaterial in the second chamber, combustion there takes place, and thegases of combustion pass into and through the electric furnace at ahigher tetnperature than before, due to the preheating of the fuel inThe hot gases hen pass out through the first mass of incandescent fueland superheat the satne. Thus with each reversal of the direction of thefiow the temperature is added to, and it is built up until the point ofmaximum efficiency is reached.

In the electric furnace-chamber the addition of the heat of the electricarc supple ments the heat of cotnbustion and effects the reduction ofthe ore or other material charged into the same, and by reason of thehigh initial temperature obtained by the regenerative flow of gasestherethrough the electrical energy is consumed only in the supplementingand finishing of the reduction, and a large amount of material can betreated in the furnace with a relatively-small expenditure of electricalpowerper pound of product.

As stated, the electric furnace may be either of the are or incandescenttype, or sometimes it may have within it an arc and at others the actionmay be purelyincandes cent. The method of operation in the present casetherefore consists in the alternate flow of gases through an electricfurnace, and through one or more masses of carbon or incendescent fuelcooperating therewith and adapted to have the gases pass through thembefore passing through the electric furnace, or in preheating the gasesin regenerative chamber before they enter the fuel furnaces,

whereby the full efficiency of the heat of combustion and theregenerative effects of the waste heat is utilized in the electricfurnace, and the material operated on therein is reduced by means of theheat of combustion employed to its fullest extent and supplemented byelectrical heat and energy.

It will be seen that this case differs from the invention set out in myapplication of date August 19, 1895, Serial No. 559,728, in thisrespect. In the present case the ore or other material is entirelytreated in the electric furnace,while in the former case referred to thematerial is first treated in a reverberatory or combustion furnace, andthe finish is given to it in an electric furnace. In both cases,however, the heat-combustion is employed as far as possible and theelectric furnace supplements and finishes the work.

An apparatus for properly putting in prac tice the invention possessesmany points of novelty which will be hereinafter fully described indetail. The leading feature thereof is an electric furnace-chambercapable of being closed in and having means for charging it with ore andoperating in conjunction therewith one or tnore fuel-chambers, allconnected so that gases can be passed through them in series and theflow from time to time reversed. Added to the foregoing there areheating-stoves for utilizing the hot waste gas for regeneration andmeans for charging the several furnaces therethrough.

In the accompanying drawings, Figure l is a longitudinal sectional viewof the furnaces, taken on the line 1 1 of Fig. 2, with theheating-stoves in the rear appearingin elevation. Fig. 2 is a sectionalplan view taken on the line 2 2 of Fig l, and Fig. 3 is a verticalsectional view taken on the line 3 3 of Fig. 1.

The electrical furnace-chamber is shown at A flanked on either side bythe fuel-chambers B B, the three chambers being in a horizontal line,with communicating flues I) b and with the gas-ports E E at the ends ofthe line of furnace-chambers. In the present case the furnace-chambersare all formed with solid-carbon walls, and collectively they form acarbon block X X, with the several chambers, lines, and passagestherefor formed therein, as clearly shown by the sections thereof in theseveral figures. This, however, is not an essential feature, it beingimmaterial how the furnace-chz'tmbcrs are constructed.

C G and D D are two pairs of heatingstoves, and a proper system offines, valves, and blowers is provided to direct and control the fiow ofthe air and gases, so that the hot gases issuing frotn one end of thefurnace can pass through one pair of regcncratorsas, for example, thestoves C and Dwhilc fresh airand fresh gas are bei ngforced through theother pair of regenerators C and D and into the opposite end of thefurnace. To this end F and G are blowers for gas and air, respectively.The flue f from the gas-blower IOC F has a cross and a butterfly-valvef, with branch flues leading therefrom into the bottom of the twoheating-stoves D D, so that the can be turned into either stove. At fthe flue has a second cross and valve therefor, the branch flues f fleading, respectively, to the ends of the furnace and the flue f leadingup to a cross and butterflyvalve f from which the fines d and 61 connectwith the upper parts of the heatingstoves D D, respectively, while theflue f is a chimney-outlet for spent gases. In like manner the flue gfrom the air-blower G has a cross and valve at g, with the branches 0 0leading to the bottom of the two heatingstoves C C, so that the air, andlikewise the hot gases, can be turned into either stove. At 9 the fluehas a second cross and valve, with branch flues g 9 leading,respectively, to the two ends of the furnace, and the flue g leading upto a cross and valve 9 from which the flnes c 0 connect with the upperends of the stoves C C, respectively, while the flue g is achimney-outlet for the spent gases. Doors at the bottom of the severalstoves are indicated at d c for admission of air for the burning of thegases therein.

The inlet and outletports E E are illustrated in the present case ascompound orifices discharging into the end chamber a flow of hot airfrom the central flue g (taking the burner E) and a flow of hot gas fromthe annular outlet around it from the gas-fluef When, on the other hand,the hot gases pass out at the end of the furnace-as, for example, at theend E'the flow divides between the two :flues f and 9 Part flows outthrough the central opening to the flue g" and part through the annularpassage to the flue f and the hot gases are conducted by the respectivefines to two of the stoves.

The two furnaces B B are counterparts of each other, and a detaildescription of one will suffice for both. The grate-bars H are for thepurpose of cleaning out the accumulation of ashes from thecombustion-chamber, and when the furnace is in operation theashpit H andall outside entrances to the fuelchamber are closed, though there may bean air-draft up through the grate-bars for a brief period when thefurnace is first started until the fuel in the chambers B B is wellignited.

At the top of the chamber there is a doublevalved charging-hopper K forthe fuel, 75 being a slide which can be withdrawn for the admission offuel into the lock-chamber 7c, and k a cup-and-cone valve to allow forthe dropping of the fuel charge into the chamber B when the slide hasbeen closed.

Referring now to the central electric furnace-chamber, L is a carbonelectrode vertically adjustable within the chamber by means of thesupportinga-od Z. This rod is shown as screwthreaded at its upperportion and fitted with a nut Z, supported in bearings and which can beturned by means of the hand-wheel Z and the sprocket-wheel-andchainconnection Z for raising and lowering the carbon pole. One of theelectric connections is made with the carbon-holder at M, and the otherconnection is made to the furnace, as at M. The lower portion of thecarbon-holder is hollow. and it is cooled by a flow of waterthereihrough.

Z' is a water-pipe leading into the bottom of the hollow holder, and lan outflow pipe therefor.

Two charging-hoppers N N are shown on opposite sides of the carbon poleto give a uniform distribution of the charge material within thefurnace-chamber and around the electrode. Each chargingspout has twovalves, so that the material can be passed in without the escape of gasfrom the furnace.

To inclose the carbon electrode and its holder, there is awater-jacketed pipe 0, ex tending up from the cover R of the furnace,with an insulating stuffing-box O for the holder-rod. The water-pipesfor the waterjacket are shown at 0 In like manner the charging-hopper Kis water-jacketed, K K being the inlet and outlet pipes therefor, andthe casing P of the furnace-l'iody is a waterjacketed shell, some of thewater-pipes therefor being shown at P P P. Cooling-coils P may beembedded in the carbon furnaceblock itself, and the central-carbon coverR and the ring-section R are provided with like cooling-coils.

S is a course of insulating-bricks for the cover, and the ring-section Rmay be of insulating materiahwith insulation between the parts of thecasing thereof at 1- The sump T is preferably low enough below thelateral gas-fines Z) l) to drop the position of the electric are orelectric-heat center below the path of the through-flowing gases, sothat the latter will not traverse directly through the Zone of highestheat, but just aboveit, forthe reason beforestated. A taphole 25 for themolten prod not is shown in Fig.

From what has preceded the operation of the furnace will doubtless beunderstood, but it will be briefly reviewed. 1 wish it distinctlyunderstood, however, that the illustration of the furnace with all itsdetails herein given is solely for the purpose of presenting a fullembodiment of the invention and that the structural features describedare not all essentials, butthat they can be omitted or modified asjudgment may dictate.

In starting the furnace the chambers B B are charged with coke andignited, and the apparatus is run with a blast of air alternating indirection of flow through the furnace until the fuel in the chambers isincandescent, or the fprnace may be started with both the air and gasblasts, or the furnace may be started solely with electrical heat in theelectrical chamber and with a reversal flow of gas therethrough. Thecoke masses in the chambers B B become regenerative bodies and receiveand store up the heat from the outflowing gases and impart it to theinflowing gas until the coke masses become highly-heated incandescentbodies. When the furnace is in operation, the gases evolved are suitablefor passing through the furnace in a reversing flow and may be blown inunmixed with air, the coke masses in this case serving entirely asregenerators and as collectors of heat. \Vhen the valves are set for theinflow of air and gas at E and the outflow of hot gases at E, the valvef is set to turn the gas from the blower F into the bottom of the stoveD, the valve f to direct it down the flue f and the valve f to send itby the flue f to the burner E. The air from the blower Gin like manneris turned into the bottom of the stove C by the valve g. It issues hotat the top and is directed down the flue g and the valve is turned tosend it by the flue g to the burner E. At the other end of the furnaceone half of the hot gases issues by the flue f to the valve f to thevalvef, and in at the bottom of the stove D, where they burn, air beingadmitted therefor through the door (1. The spent gases issue at the topof the stove and are turned up the chimney-fluef by the valvef. Theother half of the hot furnace-gases passes out through the flue g to thevalve 9 then to the valve g, in at the bottom of the stove C, where thegases are burned, the final spent gases passing up the chimney-flue g Onthe reversal of the several valves the course of the gas is via theblower F, flue f, valve f, the hot stove D, valve f", flue f valve f andflue f to the burner or entrance-duct E, the air flowing from the blowerG via the flue g, valve g, hot stove O, valve g", flue g valve 9 andflue g to the burner, while the hot furnace-gases divide between thelines f and g and pass to the stoves D and G and heat them up. When thefurnace is sufficiently heated up, the ore or other material is chargedinto the electric furnace through the hoppers N N and is fed in fromtime to time as the reduction takes place, and the product is tapped offat t to keep a body of ore in the path of the gas flowing therethrough.The through-flowin g current of hot reducinggases heats the ore to ahigh temperature before it descends to the immediate neighborhood of theelectric are or zone of reduction, and the full efficiency of the heatof combustion is thus utilized.

What I claim as new is 1. The combination in a furnace, of an electricsmelting-chamber to be charged with the material to be reduced andhaving electrodes and electric-circuit connections therewith, twochambers to be charged with fuel, lines connecting the electricsmelting-chamber intermediate with the fuel chambers, and

means for causing a reversing flow of an scriform fluid through thefuel-chambers and the intermediate electric smelting-chamber.

2. The combination in a furnace, of an electric smeltingchamber havingelectrodes and electric-circuit connections therewith, two or morefuel-chambers with the electric smelting-chamber interposed betweenthem, and with communicating flues therebetween, with a blast mechanismfor causing a flow of a gas through the series of fuel-chambers andelectric chamber, and a reversing mechanism for said gas-flow, wherebyore or other material in the electric smelting-chamber can be prcheatedby a regenerative gas-flow.

3. The combination in a furnace, of an electric smelting-chamber havingelectrodes and electric-circuit connections therewith, two fuelchamberswith the electric smeltingchamber therebetween and communicating fluestherefor, each of said chambers having gas-tight charging-ports,together with a draft mechanism for causing a reversing flow of gasthrough the series of chambers.

f. The combination in a furnace, of an electric smelting-chamber havingelectrodes and electric-circuit connections therewith, a pair of hotblast stoves, and a chamber to be charged with fuel, with fluesconnecting the hot-blast stoves with the fuel-chambers, and thefuel-chamber with the electric smeltingchamber, and thecontrolling-valves therefor, as and for the purpose set forth.

5. The combination inafurnace, of an electric smelting-chamber havingelectrodes and electric-circuit connections therewith, a pair ofhot-blast stoves, and a pair of fuel-chainbers, with flues connectingthe hot blast stoves with the fuel-chambers and the latter with theelectric smelting-chamber, means for reversing the flow of gases,together with valves therefor, whereby a reversing flow of hot gases canbe sent through the fuel-chambers and the smelting-chamber, as and forthe purpose set forth.

6. The combination in a furnace, of an electric smelting-chamber thesame having electrodes and electric-circuit connections therewith, andtwo fuel-chambers formed in asolid block of carbon with connectingflucs, the fuel-chambers flanking the smelting-chamber, and reversingmeans for causing a flow of gas through or between the series ofchambers.

In testimony whereof I a'llix my signature in presence of two witnesses.

ALFRED H. OOYVLES.

W'itnesses:

FRANK M. ASHLEY, STORY B. LADD.

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